Expander nut having three surfaces of different inclination



EXPANDER NUT HAVING THREE SURFACES OF DIFFERENT INCLINATION Filed March so, 1953 March 5, 1957 w. J. LEWIS ETAL 2 Sheets-Sheet 1 I'IIIIIIIIIIIIQIIIIIIIIIII:

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FlqiO March 5, 1957 w. J. LEWIS EIAL 2,733,673

EXPANDER NUT HAVING THREE SURFACES OF DIFFERENT INCLINATION Mi k WARREIIQI ELMO F. HUSTQN United States Patent 9 EXPANDER NUT HAVING THREE SURFACES OF DIFFERENT INCLINA'I'ION Warren J. Lewis and Elmo F. Huston, Mansfield, Ohio,

assignors to The Ohio Brass Company, Mansfield, Ohio, a corporation of New Jersey Application March 30,1953, SerialNo. 345,422

3 Claims. (Cl. 852.4)

This new and useful invention relates to bolts of the expansion type and has a particular application for supporting the roofs of mines, thus avoiding the use of beams, pillars, etc., which take up room and interfere with mining operations.

A form of the conventional type of expansion bolt is disclosed in application Serial Number 201,651, now Patent No. 2,667,099 filed December 19, 1950, by Warren J. Lewis. It has a split or divided tubular shaped casing with a tapered interior wall capable of being expanded, an expander forming a frnstnm of a cone, and a stud threaded into the expander by means of which the expander is manipulated relative to the casing; by drawing the expander into the casing, the casing is expanded into engagement with the wall of the drilledopening in which the device is installed.

In the improved bolt herein disclosed, the casing and stud may be of the same construction as described above but the expander is constructed upon entirely new principle which functions with several improved results as compared with the usual functions of a plainconical or wedge shaped expander and beneficially affects the functioning of the bolt.

As compared with the conventional expansion bolt,

the bolt herein disclosed with the improved type of expander is adapted to more efii-ciently meet the varying conditions of installation such as openings of varying diameters having. hard unyielding walls or walls of soft material.

The improved expander herein disclosed may be said to be a conic; that is, having-the form of, or resembling, the frustumof a cone, but which is composedof two or more superimposed frustums of a cone. -E-ach fiustum is herein referred to as a zone and the preference i for three zones and is so considered in the description to follow.

The herein described expander has an upper and lower base and the bases of the intermediate zone are common with the adjacent bases of the respective upper and lower zones.

'For the sake of a better term for the herein described preferred form of expander, it is referred to at times in the description and the claims as a conic, since it re sembles or has the formof a cone composed of two or three zones, preferably three, and each zone has a separate function which it performs either separately or in cooperation with the other zones.

There are a number of advantages of the above type of expander over the usual or one zone expander that is the frustum of a cone, and such advantages will be referred to later, but a description of the improved bolt will help one to better understand the advantages of the conic expander over the conventional type.

The improved expansion bolt is fully set forth in the following description with reference to the accompanying drawings and the features of novelty which characterize 2,783,673 Patented Mar. 5, 1957 the. invention will be pointed out later herein and in the claims forming, a part of the specification.

Referring to the d'rawing-- Fig. I is a view-in elevationof the body portion only, for clarity, of the expander.

Fig. 2' is a view in elevation of the complete expander.

Fig. 3 is a view in elevation. and partly broken away, of the complete expander taken at from Fig. 2.

Fig. 4 is. a top view of Fig. 2 showing oppositelydisposed. longitudinal. slots.

Fig..- 5 is a bottom. view of Fig. 2 showing oppositely disposed slots and. ribs.

Fig. 6- is aside view in elevation. of the complete. bolt constructed in accordance with the invention before positioning in an opening in a mine roof.

Fig. 7 is another side view in elevation of. the complete bolt shownin. Fig. 6 taken at 90. therefrom but with the casing collapsed as in- Fig. 8.

Fig. 8. is a side view of Fig; 6, collapsed and positioned in: an opening in a boredhole in a mine roof.

Fig. 9 isan outer or upper end view of Fig. 6.

'Fig. 1-0 is a longitudinal. view of Fig. 8 taken ona line corresponding to line Ill-10 of Fig. 9.

Fig. 1:1 is a view similar to Fig. 10 but the expander is positioned farther within the casing.

Fig. 12. is a view similar to Fig. 11 but the expander has advanced its full depth into the casing.

'Fig. 13 is similar to Figs. 11 and 12 but the expander has advanced well into the casing.

Fig. l4-is a side view of the: expander of Fig. 1 using a smooth. surface in place of a plurality of conical surfaces.

The expander E, omitting a number of elements for the sake of clarity, is shown in Fig. 1' as having integrally formed superimposed zones 1, 2 and 3. Each zone is a frnsturn of a cone. having distinct conical surfaces a, b and c respectively which are angularly disposed tothe axisx' y of the expander as indicated by e, f and 3 respeetively.

The expander has exposed upper base 4 and exposed lower base 5 and the demarcations' between the zones are indicated by common lines 6 and 7; all said bases and the planes of the demarcations are parallel. The expander is preferably formed of malleabilized cast iron, a forging of iron or of other non-brittle metal.

The side or lateral surface of the expander of Fig. 1, while composed of a plurality of conical surfaces, is sub s-tantially convex, and that of Fig. 14 (later described) is convex; therefore, the term convex applies to the side surface, taken as a whole, of the expander of Figs. 1 and 14 as contrasted to the conical surface of a one zone expander, a frnstum of a cone.

The expander shown in Figs. 2 to 5 inclusive consists of a body, or a solid of revolution and is provided with oppositely disposed slots 10 parallel to the axis x-y and with oppositely disposed ribs 11 which project from the surface of the expander parallel to the axis xy and are spaced circumferentially 90 from the slots 10. An axially threaded opening 12 is provided to receive a threaded stud.

Referring now to Figs. 6 to 9 inclusive which disclose the assembled bolt, there is shown an elongated tubular shaped casing 15 formed of two like halves 16 preferably of a malleable or bendable metal, separated longitudinally. Each half is provided with a slot 17 and the adjacent longitudinal edges of the halves 16 are spaced to form the slots 18. This provides a casing with four yield-able prongs 19 (Fig. 9). The halves 16 are pivoted at their inner ends permitting their outer ends to separate radially. Other forms of casings may be used.

To hold the halves 16 in assembled relation, a bail 20 preferably of spring steel is provided which has its bight 21 spaced beyond the outer end of the casing and its arms 22 extending along side of the casing with the free ends of the arms secured to the halves 16 at their inner ends by means of compressed lugs 23. The arms 22 rest in the slots 17 and the bail is so formed that when secured to the halves of the casing 15, the innerends of the halves 16 will be yieldably held together and the outer ends yieldably held apart a predetermined amount as shown in Figs. 6 and 9. When the outer end of the bolt is collapsed to enter a roof opening, the casing will have the same diameter throughout its length.

The ribs 11. on the expander will operate longitudinally in the slots 18 as the expander is moved longitudinally relatively to the casing, and prevent relative rotation of the expander and the casing. The arms 22 will rest in the slots of the expander such that the expander is free to move without affecting or being affected by the bail.

The casing is provided with an obliquely ribbed outer surface 24 to better grip the wall of the opening in which the bolt is installed. The inner surface 25 is tapered with respect to the longitudinal axis of the casing, to be engaged by the expander, whereby the diameter of the opening through a portion of the casing gradually decreases downwardly, and the tapered surface is such that it cooperates with the expander to force the casing against the walls of the opening.

The expander E is mounted to be moved within the hollow of the tubular casing and the outer end of the stud threadably engages the threaded opening 12 of the expander.

When it is desired to install the assembled bolt to support a mine roof, an opening is drilled of proper diameter and depth, the diameter being preferablyslightly larger than the diameter of the bolt when the casing has been manually collapsed against the outward pressure of the bail, as disclosed in Fig. 8 (compare with Fig. 6).

The manually collapsed casing is installed in the roof opening and immediately tends to return to its normal condition (Fig. 6) pressing against the wall of the opening. Upward pressure applied to the stud 30, the end of which protrudes slightly beyond or is flush with the outer end of the expander, forces the end of the stud or the expander against the night 21 of the bail, thereby raising the casing, expander and stud into proper position in the opening.

The normal outward pressure of the casing against the wall of the opening, due to the spring in the bail, will keep the casing from rotating relatively to the wall of the opening until pressure from the expander enlarges the casing.

The stud will continue to press against the bail, thus preventing the casing from moving longitudinally downward, but as the stud rotates in the proper direction, the expander moves into the casing, thereby expanding the same.

Figs. 10 to 13 represent several relative positions of the casing and expander to the bolt positioned in a mine roof opening slightly larger than the bolt, the roof being considered to be of soft material. These figures all show a longitudinal section taken on the line 10-10 of Fig. 9, at different stages of the manipulation of the expander, to better show the full section of the wall of the casing which increases in thickness relatively to the expander. Figs. 1013 do not disclose the surface ribs 24.

In Fig. 10, the bolt and parts are shown as first positioned in the opening 36; the stud is shown as contacting the bail, the casing is collapsed to the diameter of the opening and the .expander is in its outermost position with zone 3 entered in the casing. Zone 3 acts to guide the expander into the casing in some cases when the ex pander end might not initially be entered in the casing;

The wall of the expander of the conventional bolt using a straight conical surface, when under "sufficient tension on the stud will be forced inward and bind upon the stud, and if the pressure is sufficient the friction between the stud and expander may be so great as to prevent the operator securing the necessary tension to properly support the roof. Such tensions may run as high as 10,000 pounds or greater.

Comparing the improved expander with the conventional expander (frustum of a cone), if the height of the expander is the same and the upper and lower bases are the same and if the conical surfaces of the zones of the improved expander are arranged along the lines of those disclosed in Fig. l, the diameter of the middle zone 2 will be greater than the corresponding portion of the conventional expander, and if the tension on the studs is the same, the improved expander will better resist the tendency for the improved expander to collapse and bind on the stud. The resistance of the improved expander to collapse and bind on the stud is the result of the improved shape of the conic surface of the expander.

Referring to the previous paragraph, the sum of the areas of the conical surfaces of zones 1, 2 and 3 of the improved expander is greater than the area of the conical surface of the one zone conventional expander, consequently with a given stress on the stud, the stress per unit area is less on the improved expander than on the irustum of a cone expander, therefore the improved ex pander resists collapse to a greater degree than the con ventional expander.

The surface of zone 3 of the expander makes a greater angle with the axis of the bolt than the surface of zone 2, and the surface of zone 2 makes a greater angle with the ax s of the bolt than the surface of zone 1. As will be more particularly explained in what follows, the angle which the surface of zone 1 makes with the axis of the bolt is substantially the same as the angle which the inner surfaces of the prongs 19 make with the axis of the bolt when the outside surface of the casing is substantially cylindrical as illustrated in Fig. 8.

When the expander is moved into the casing the first contact between the expander and the casing is with a zone of the outer surface of the expander which makes an angle with the axis of the bolt which is greater than that of zone 1. This tends to spread the prongs toward the wall of the opening and they are spread as rapidly as is feasible. Early pressure of the casing against the wall of the opening by means of the expander is desirable in order to prevent rotation of the casing in the opening.

Finally the inner surface of the prongs contacts the surface of zone 1. These two surfaces makes substanhardly the same angle with the longitudinal axis of the casing so that when the prongs are pressed against this surface the opposite or outside surface of the casing is substantially cylindrical. The effect of this is that when the entire expander has moved into the opening, as illustrated in Fig. 12, the outer ends of the prongs are pointed upwardly and the outer surface of the casing opposite this portion of the prongs is cylindrical.

The grip of the bolt on the Wall of the opening is due to the pressure of the wall of the casing against it. The prongs taper complementarity to the expander so that the farther the expander is moved into the casing the larger the-outer diameter of the portion of the casing which surrounds the expander. Figure 13 shows the expander well within the casing with the prongs extending upwardly above the top of the expander. There is no direct outward pressure against any portion of the casing which is above the expander. It is only the portion of the casing opposite the expander which is pressed into the wall of the opening. The expander is solid so it can not give and the whole. of the pressure is exerted outwardly against end of the expander is cylindrical. This surface of expander is herein identified as zone 1.

Merely as an example of a concrete device, and not for the purpose of limiting the scope of this invention, and referring to Fig. l, the depth or height of zones 1, 2 and 3 may be /2, and A" respectively and the angles of the conical surfaces to the longitudinal axis xy may be respectively 3 /2, and 14. When the casing is collapsed as in Figs. 7 and 8, the angle of its inner surface may be 3% to the axis x--y. These dimensions are merely for illustrative purposes but may be such as required to carry out the invention herein disclosed; these dimensions are disclosed in Fig. l and are practical for the expander to be used with a stud.

The expander shown in Fig. 14 is similar to that of Fig. 1 except that the three zones are not distinct but merge smoothly one into the other. The expander may be in the form of a frustum of an ellipsoid such as would be approximated by the expander of Fig. 1, and has a cross section which is very close to that of the expander of Fig. 1, particularly at the upper or larger end thereof.

The improved bolt herein disclosed, which is shown as installed in a mine roof opening of slightly greater diameter than the normal diameter of the bolt, is adaptable for installation in openings of somewhat larger diameter and in which the roof may be of hard or soft formation.

While two closely allied expanders are described and illustrated, it will be apparent to those skilled in the art that modifications of the invention may beproduced which will fall within the scope of the invention as set forth in the appended claims.

It is claimed:

1. An expansion device for holding the end of a bolt in a blind recess having a yieldable wall, comprising elongated malleable shell means having a plurality of yieldable prongs with supporting means at the lower end thereof and a longitudinal central opening for receiving the bolt, the yieldable prongs being spaced about the opening, the outer surfaces of the prongs having ridges formed therein for gripping the walls of the recess, and an expander at the upper end of the shell means com prising a solid member adapted to enter entirely within the shell, which solid member is provided with a threaded longitudinal opening for receiving the bolt, and ribs exthe tending laterally between the prongs to hold the expander against rotation with respect to the shell means, the outer surface of said solid member being formed with three separate zones, said zones forming respectively a downwardly narrowing portion at the bottom part of the member for guiding the expander into the opening in the shell, a relatively slight downward taper along the upper part of the member for holding the prongs in outward engagement with the walls, and an intermediate zone having a taper intermediate that of the upper part of the member and the general slope of the narrowing portion at the bottom part of the member, said relatively slight downward taper and intermediate taper each being substantially the frustum of a cone, said relatively slight downward taper along the upper part of the member and the inner surfaces of the ends of the prongs when the outer surfaces of the prongs are cylindrical being substantially equal so as to distribute the compressive stress uniformly along and about the upper part of the member after the expander has been drawn into the shell means with the upper end of the member below the upper end of the prongs; the malleability of the shell permitting it to conform to the surface of the solid member of the expander and causing the prongs of the shell to be directed inwardly, as the solid member passes through it.

2. The expansion device of claim 1 in which each of the three zones is substantially the frustum of a cone.

3. The expansion device of claim 1 in which the zones of which the outer surface of the solid member is formed, from the bottom to the top of the solid member are frustums of cones which slant at angles to the longitudinal axis of the member of substantially 3 /2 degrees, ten degrees and fourteen degrees respectively.

References Cited in the file of this patent UNITED STATES PATENTS 332,701 Craig Dec. 22, 1885 900,462 Aderer Oct. 6, 1908 1,650,956 Ogden et a1. Nov. 29, 1927 1,654,346 Ogden Dec. 27, 1927 2,381,050 Hardinge Aug. 7, 1945 2,667,099 Lewis Jan. 26, 1954 

